I. Field of the Invention
The present invention relates to apparatus for forming briquettes from combustible raw materials and, in particular, to improved apparatus constructed to selectively expose portions of the ram slide path during maintenance and to prolong the time between maintenance. These ends are achieved through the redesign of various components and the inclusion of water and oil cooling of the ram slide path.
II. Discussion of the Prior Art
With the increasing cost of energy, efforts have been directed toward developing alternative energy sources and one such effort consists in the fabrication of burnable briquettes from waste combustible raw materials, such as sawdust, corn stalks, waste paper and other combustible "bio-mass", materials that are available in economical quantities. Because such materials are typically rather voluminous relative to their BTU content, it is necessary to reduce the raw material to a size that provides a relatively high BTU content per unit of volume and a form that is readily adaptable to burning. A particular form that has been found to be desirable is a puck-like briquette. Such briquettes may be stored and/or burned by themselves or in combination with various other fuels in conventional furnaces. Alternatively, it may be necessary to adapt an available furnace to be compatible therewith.
One type of commercially available equipment for forming such briquettes is a machine produced by the SPM Corporation. This equipment generally comprises apparatus having a power-driven flywheel that operates in conjunction with a crank shaft and connecting rod to transfer power, via a crosshead assembly, to a compression ram. Waste matter entering a compression chamber is thence caused to be compressibly rammed into an uncooled, split, forming die and wherefrom the compressed material exits via a clamped split-die assembly.
In using equipment of the above type, however, problems have arisen in that the available assemblies have not been designed from the standpoint of facilitating normal maintenance. It is principally in this regard, that the present invention has been developed as an improvement to ram driven briquette making apparatus. That is, the present invention facilitates normal maintenance via a plurality of housing covers and prolongs the time between maintenance by providing cooling at critical heat generating portions of the apparatus, by separating the ram scraper rings and oil seals and by attention to the manner in which the reciprocating ram is supported at the points of maximum load.
Problems have arisen in the aforementioned SPM machine in that normal wear items, such as ram oil seals, scraper rings and the split dies, and which are not readily accessible, due to machine designs that integrate the ram assemblies within closed housings. Thus, the mere inspection or changing of individual parts in that prior art system requires the disassembly of the entire ram assembly. Wear is further aggravated in the SPM machine because of metal-to-metal contact between the scraper rings and the ram which, even though they are of dissimilar metals, causes grooves to form in the ram. This allows biomass material to enter the oil system and/or oil is permitted to leak into the compression chamber. Because the prior art apparatus is dependent upon an oil injection system for delivering a specified volume of oil to the wear points, lubrication is hampered by the accumulation of dirt and debris in the oil sump which tends to plug the injectors and/or cause leakage at the seals. The prior art apparatus as represented by the SPM machine also employs a crosshead assembly that has a relatively small wedge shaped horizontal slide area which is suspectible to wear as the ram is driven horizontally to and fro. Still further, essentially no cooling of the ram has been provided in that prior art design. This adversely affects the life of these components due to the high heat produced through the compression process. The raw material feeder assembly of the prior art machine also has proven to be subject to frequent jamming wherein the ram may be caused to seize-up. These seizures are not easily cleared without the tedious and time-consuming dismantling of the apparatus.
To overcome these problems, the present improved apparatus was conceived. It generally provides an improved briquette forming apparatus which overcomes the foregoing problems, facilitates maintenance and reduces down-time. Specifically, the present invention provides for a multi-segmented housing that surrounds the ram slide assembly and permits the exposure and periodic maintenance of the various critical wear elements integral to the ram. That is, split housing covers are provided in the regions of the split die, oil seals, ram bearings and scraper rings which are the parts most subject to wear and maintenance. Further, the ram scraper rings have been segmented to provide primary and secondary scraping regions. By employing scrapers of dissimilar metals, ram wear is decreased and longer seal life results. Also, the accumulation of dirt within the sump is avoided. The housing cover in the region of the split die has also been designed to be liquid cooled, while the ram guide housing has been modified to provide oil cooling. Appurtenant temperature sensors and control apparatus monitor and control the temperature thereof. A self-clearing prefeeder assembly is also provided with a controllably reversing auger, whereby auger direction is reversed upon the detection of jams and resumed after a delayed period.